2003 Eddie bower expo, 165,000 miles 5.4 motor. Bone stock down to the Radio.
last year it would develop an intermittent engine misfire. along with this miss the rear speakers would pop. Even with the head unit for the stereo off, the speakers would still pop. There is a factory amp somewhere that i believe to be causing the pop. I noticed that when i switched the a/c on and off I could make it misfire and and the speakers pop. I deducted it was having power delivery problems from the battery. I cleaned the battery cables and replaced the battery end on the positive side. The miss and the speaker pop went away. It came back about a year later. I have now replaced the Power distribution block cable, and the main positive/negative cable assembly with OEM cables. the problem persists. I ordered a new Battery to Alternator cable and plan on replacing that as soon as it arrives. My question is: What else might cause this problem? Could a bad coil pack on the motor be going to ground and zapping the power causing the speaker to pop? The voltage is 12.1 sitting, jumps up to 14.3 at idle when running. I watched the voltage on the IDS for a while and didn't get anything unusual from it. any thoughts would be appreciated. I have IDS and plenty of test tools to check things.

 

Also, there are no codes and it passes all IDS checks.

 

I might have just solved this. When I put the new Ford cables on I used the wire type terminal cleaner until I got shiny lead on the battery posts. I just took the shaving type cleaner and cleaned the posts shaving some lead off, added a lead post shim to the Positive side and re-tightened the battery cables ends. The miss and speaker pop went away. Just took it on a 10 mile drive and it runs perfect. The battery is 4 years old, passes all load tests but maybe is getting a little marginal to have anything not perfect.